Assessment of diastolic left ventricular filling by echocardiographic automated border detection and comparison with radionuclide ventriculography

Detection of left ventricular systolic and diastolic abnormalities in patients with coronary artery disease by color kinesis

BACKGROUND

Color kinesis (CK) is a recently developed echocardiographic technique based on acoustic quantification that automatically tracks and displays endocardial motion in real time and has been used in initial studies to improve the evaluation of global and regional wall motion.

HYPOTHESIS

For further validation of the use of CK for analysis of segmental ventricular dysfunction, we assessed its sensitivity and specificity for detection of regional systolic and diastolic wall motion abnormalities in patients with coronary artery disease (CAD).

METHODS

Two-dimensional (2-D) echocardiography and CK were used to study 15 normal subjects and 63 patients with technically good quality echocardiographic tracings, who underwent coronary arteriography within 1 month of echocardiography. Significant (> 70% luminal diameter stenosis) CAD was present in 50 patients (79%).

RESULTS

Color kinesis tracked endocardial motion accurately in 93% of left ventricular segments. Wall motion score, systolic segmental endocardial motion (SEM), and the time of systolic SEM (tSEM) and diastolic (tDEM) segmental endocardial motion were calculated. Intra- and interobserver variability were within narrow limits. SEM and tSEM were significantly lower and tDEM was significantly higher in the patient population than in the control group (p < 0.001). Comparison between CK and 2-D echocardiography showed a correlation coefficient of 0.81 between the two techniques. The score was identically graded in 74% of segments, with concordance of 82% in diagnosing segments as abnormal. Interobserver concordance was 86% for CK (r = 0.85) and 81% for 2-D echocardiography (r = 0.80). The sensitivity and specificity of systolic and diastolic CK parameters for the detection of CAD were 88 and 92% and 77 and 85%, respectively. The positive predictive values were 93 and 96%, respectively, the negative predictive values were 63 and 73%, respectively, and the overall accuracy was 86 and 91%, respectively.

CONCLUSIONS

Our data suggest that CK is a feasible and sensitive technique for identifying regional systolic as well as diastolic wall motion abnormalities in patients with CAD.

Normal values of left ventricular systolic and diastolic function derived from signal-averaged acoustic quantification waveforms: a multicenter study

Automated border-detection techniques such as acoustic quantification have proven accurate and useful for quantifying left ventricular (LV) function. We acquired LV acoustic quantification waveforms from the parasternal short-axis window in 140 healthy patients in the age range of 16 to 78 years. Signal-averaged waveforms were analyzed for parameters of systolic and diastolic performance. The average fractional area change was 54 +/- 12%, and there were no significant changes in LV systolic function in the age range studied. There were significant changes in diastolic parameters with aging. The percentage of contribution to total LV filling occurring during atrial filling nearly tripled during the 6 decades studied, from 13% in the youngest cohort to 36% in the eighth decade of life. This study provides normal reference values for systolic and diastolic parameters of LV function determined from signal-averaged acoustic quantification waveforms acquired from the parasternal short-axis view in adult and adolescent patients over a wide age range.

Assessment of Global and Regional Left Ventricular Diastolic Function in Hypertensive Heart Disease Using Automated Border Detection Techniques

Acoustic quantification (AQ) and color kinesis (CK) are techniques that involve automated detection and tracking of endocardial borders. These methods are useful for the evaluation of global and regional left ventricular (LV) systolic function and more recently have been applied to evaluating LV diastolic performance. Assessment of diastolic dysfunction in hypertensive heart disease is a relevant clinical issue in which these techniques have proven useful. The diastolic portion of left atrium and LV AQ area waveforms are frequently abnormal in patients with left ventricular hypertrophy (LVH). Left ventricular AQ curves consistently demonstrate reduced rapid filling fraction (RFF) and peak rapid filling rate (PRFR), elevated atrial filling fraction (AFF), peak atrial filling rate (PAFR), and reductions in the ratio PRFR/PAFR. Acoustic quantification complements traditional Doppler echocardiographic evaluation of global diastolic function. Many patients with significant LVH and normal Doppler diastolic parameters can be identified as having diastolic dysfunction with AQ. In addition, CK has allowed the evaluation of regional diastolic performance in hypertensive patients. Regional filling curves obtained from CK have demonstrated that endocardial diastolic motion is commonly delayed and heterogeneous in patients with LVH.

Analysis of cardiac left-ventricular volume based on time warping averaging

The cardiac left-ventricular (LV) volume signal, obtained by acoustic quantification, is affected by noise and respiratory modulation, resulting in a large beat-to-beat variability that affects the computation of LV function indices. A new method is proposed to improve the evaluation of LV indices by applying a signal averaging technique based on dynamic time warping to consecutive LV volume waveforms. Volume signals obtained from ten normal young (NY) subjects (mean age +/- SD: 25+/-5 years) were used to evaluate the performance of this algorithm. To evaluate its clinical utility, the effects of ageing and pharmacologically induced changes on LV function were assessed by studying, respectively, ten normal (N) adult subjects (age 64+/-8 years) and ten patients with dilated cardiomyopathy during a control and low-dose dobutamine (10 microg kg(-1) min(-1)) study. Indices of LV function were highly consistent, with a variability of less than 8%, even when only 16 beats were averaged, independently of their selection inside the whole recording. When compared with beat-to-beat measures, the averaging of 16 beats significantly reduced (by more than 50%) the interbeat variability of all indexes. Expected alterations in both diastolic and systolic function were evidenced both with ageing (peak filling atrial contraction and ejection rates: from 275+/-77 mls(-1), 76+/-30 ml s(-1) 230+/-70 mls(-1), respectively, in NY, to 160+/-33 mls(-1), 125+/-39 mls(-1), 163+/-54 mls(-1) in N) and with dobutamine (peak filling and ejection rates from 160+/-72 mls(-1) and 183+/-86 mls(-1) respectively, in control, to 253+/-75 mls(-1) and 251+/-105 mls(-1) with dobutamine). Signal averaging with time warping allows fast and improved assessment of LV function.

Transthoracic and transesophageal echocardiography in the hemodynamic assessment of patients with congestive heart failure

All methods for estimating the severity of heart failure, such as clinical and radiographic examination, measures of ventricular performance, and exercise capacity, when used independently, have major limitations. Echocardiography can be used, not only to assess left-ventricular ejection fraction but also other determinants of prognosis (i.e., left-ventricular size and shape, estimation of left atrial and pulmonary artery pressures, right side involvement). The availability of continuous-wave Doppler has permitted us to evaluate pulmonary artery systolic pressure from tricuspid regurgitation, and this contributes to additional powerful data. In long-standing heart failure, pulmonary artery wedge pressure is a predictor of survival, and aggressive therapy to reduce wedge pressure improves survival. Noninvasive estimation of left-atrial pressure and left-ventricular filling pressure have been attempted by continuous-wave Doppler echocardiography in patients with heart failure and mitral regurgitation and by tissue Doppler imaging at the mitral annulus level. A significant relation has been reported between profiles of pulmonary venous flow and left-atrial pressure, but pulmonary venous flow indexes can be better assessed by transesophageal echocardiography (TEE) in terms of detection rate. It has recently been recognized that TEE can provide valuable information on intracardiac hemodynamics and ventricular function. Two-dimensional evaluation of ventricular function and pulsed- and continuous-wave Doppler recordings from the pulmonary artery, pulmonary vein, and mitral inflow are combined to provide these data, which are both qualitative and quantitative, and permit estimation of ventricular ejection fraction, left-atrial pressure, and cardiac output. It would be important to be able to stratify patients with congestive heart failure according to groups with the highest risk for early death because heart transplantation or aggressive medical treatment could be specifically applied to this population. Serial echocardiographic evaluations of the classic variables of systolic left-ventricular function as well as Doppler transmitral flow may be useful in monitoring the progression of the disease and the effects of medical treatment. The degree of pulmonary hypertension is independently associated with the restrictive left-ventricular diastolic filling pattern and with the degree of functional mitral regurgitation. Future studies on the impact of these hemodynamic variables on the outcome of patients with left-ventricular dysfunction are desirable.

Assessment of Right Ventricular and Right Atrial Systolic and Diastolic Performance Using Automated Border Detection

Noninvasive assessment of right ventricular (RV) function is important clinically, but current techniques have limitations. Acoustic quantification (AQ) is an automated endocardial border detection technique that allows continuous determination of RV and right atrial (RA) area waveforms and may be useful for the assessment of RA and RV systolic and diastolic performance. Fifty patients (10 normal, 40 with RV pathology) were studied. Signal-averaged RA and RV AQ area waveforms were obtained and analyzed to compute parameters of diastolic and systolic function. All groups demonstrated significant diastolic dysfunction on the RA AQ waveform as manifested by a reduced percentage of passive atrial emptying and increased dependence on active atrial emptying. Abnormalities of diastolic performance were noted in all subgroups on RV AQ analysis as evidenced by a reduction in the percentage of ventricular filling occurring during early diastole and an increased contribution from active atrial contraction. This study demonstrates the feasibility of using automated analysis of signal-averaged RA and RV area waveforms for the evaluation of RV systolic and diastolic performance. This technique identified significant systolic and diastolic dysfunction in four groups of commonly seen right heart pathologies including biventricular heart failure, pulmonary hypertension, pressure and volume overloaded RVs, and biventricular hypertrophy.

Evaluation of Left Ventricular Diastolic Performance Using Automated Border Detection

Acoustic quantification (AQ) is a noninvasive technique which provides online left ventricular (LV) area/volume waveforms. The filling portion of the AQ waveform can be used to assess LV diastolic properties. Analysis of signal-averaged AQ curves enhances the waveforms and allows reliable, quantitative, and automated analysis. From signal-averaged AQ LV waveforms, the phases of diastole can be easily detected and several parameters of diastolic performance calculated. Analysis of signal-averaged LV waveforms is complementary to that of LV AQ analysis. AQ has been used to identify diastolic dysfunction in patients with LV hypertrophy and systemic hypertension. Normal values of these parameters are age dependent and reference values will soon be available.

Acoustic Quantification Today and Its Future Horizons

We briefly review previously published work based on the uses of acoustic quantification (AQ) or validation of this technology. We also discuss the limitations of AQ in a critical review of the literature, including operator dependency, signal noise, and low temporal resolution. We describe some enhancements made to AQ software to address these limitations and improve the accuracy of this technique, including digital beam processing, harmonic imaging, and signal averaging. Several anticipated applications are also briefly described for those interested in the future development of this technology. These future applications include noninvasive long-term monitoring of ventricular function and objective assessment of regional ventricular wall motion in two and three dimensions.

Comparison of echocardiographic acoustic quantification with off-line manual tracing for determining left ventricular volume and ejection fraction in pediatric patients

Echocardiographic measurement of left ventricular systolic and diastolic volume and ejection fraction in pediatric patients by acoustic quantification using automated border methods compares well with measurements done by manual trace. The time necessary for completion of measurements was similar for the two methods.

Age dependency of left atrial and left ventricular acoustic quantification waveforms for the evaluation of diastolic performance in left ventricular hypertrophy

We evaluated diastolic performance in 50 normal subjects and 50 patients with concentric left ventricular (LV) hypertrophy. Age-dependent normal values were determined for LV and left atrial (LA) acoustic quantification parameters. Pulsed wave Doppler echocardiography was also performed on all subjects. Patients with LV hypertrophy had higher peak velocities of atrial contraction and atrial contributions to filling. The acoustic quantification waveforms revealed lower rapid filling percentage of total filling and lower peak rapid filling rates. The LA acoustic quantification analysis confirmed the dependence on active atrial emptying in the patients with LV hypertrophy. There were significant correlations with age for most of the LV and LA acoustic quantification parameters. Acoustic quantification provided confirmatory results in subjects with an abnormal relaxation or restrictive Doppler pattern. In subjects with a normal Doppler pattern, the acoustic quantification was of added diagnostic value, identifying abnormalities in 77% to 80% of the patients.

Acoustic quantification indexes of left ventricular size and function: effects of signal averaging

BACKGROUND

The aim of this study was to evaluate the clinical utility of using signal-averaged acoustic quantification (SAAQ) waveforms for improved assessment of left ventricular (LV) size and function.

METHODS AND RESULTS

Four separate protocols were performed in 47 subjects. SAAQ waveforms were used to assess alterations in LV function induced by dobutamine (15 microg/kg per minute) and esmolol (200 microg/kg per minute) in eight normal subjects. Subsequently, we analyzed SAAQ waveforms obtained in 12 patients with LV dysfunction secondary to dilated cardiomyopathy and 12 age-matched normal subjects. Finally, we developed computer software for monitoring of LV function on the basis of continuous acquisition and repeated analysis of SAAQ waveforms. We compared the interbeat variability in indexes of LV function obtained from raw AQ and SAAQ during 10 minutes of steady-state monitoring in eight patients undergoing transesophageal echocardiography. The feasibility of long-term monitoring in the intensive care setting was then studied in seven patients undergoing abdominal surgery. Our analysis tracked variations in LV function induced by dobutamine and esmolol. Significant differences in all measured indexes were found between normal subjects and patients with dilated cadiomyopathy. Signal averaging during steady-state monitoring significantly reduced the interbeat variability of all indexes (21% to 42%). In the operating room, the SAAQ monitoring system tracked hemodynamic changes in close agreement with invasive measurements.

CONCLUSIONS

SAAQ allows fast and easy quantification of LV function and can track hemodynamic trends in the operating room setting.

Estimation of Right Atrial Volume and Function by an Online Echocardiographic Edge Detection System

To define the accuracy of real-time two-dimensional echocardiographic imaging with automatic border detection (ABD) for the assessment of right atrial volume and function, we studied with ABD echocardiography 29 healthy subjects and 43 patients with sinus rhythm and various forms of heart disease. Twenty-three patients had right ventricular (RV) dysfunction (fractional area change < 45%), and 20 had RV hypertrophy from pressure overload. Doppler color flow imaging disclosed moderate-to-severe tricuspid regurgitation (TR) in 20 patients and trivial or no TR in 23. The ABD-derived end-diastolic (EDV) and end-systolic (ESV) volumes by the method of discs were used to compute fractional indexes of right atrial (RA) volume changes. Right atrial emptying fraction (RAEF) percent [(ESV - EDV)/ESV x 100] was calculated. The ABD-derived EDV and ESV correlated well with conventional offline measurements of two-dimensional echocardiographic images in the 43 patients (r = 0.94 for the end-diastolic values; r = 0.93 for the end-systolic values). Intraobserver and interobserver variability showed a high correlation between different measurements (r = 0.97 and 0.90, respectively). RA volumes were significantly higher in the patient population than in the control subjects (148.9 +/- 66.7 ml vs 43.1 +/- 9.2 ml, P < 0.0001). The right atrial emptying fraction (RAEF) was higher in patients with RV pressure overload than in normal subjects (61% +/- 11% vs 46% +/- 9%, P < 0.05) and lower in those with RV dysfunction than in the control subjects (29% +/- 7% vs 46% +/- 9%, P < 0.01). In both groups (RV pressure overload and RV dysfunction), RAEF was higher in patients without or with trivial TR compared with those with significant TR (29% +/- 7% vs 23% +/- 6%; 61% +/- 11% vs 42% +/- 7%; P < 0.05). Thus, changes in right atrial volume and function can be measured noninvasively by the ABD method. This imaging technique may prove to be useful for assessing right atrial size and function under different physiological and pathological conditions and for identifying factors that influence atrial function in right ventricular diseases.

Diastolic heart failure: standard Doppler approach and beyond

Evidence of normal systolic left ventricular function has been reported in up to 30-40% of patients with clinical signs of congestive heart failure, suggesting that diastolic dysfunction is an important predictor of prognosis and mortality. Doppler echocardiography as a noninvasive diagnostic procedure is able to provide immediate and relevant information on functional and structural changes underlying the clinical syndrome of heart failure. Four distinct early filling/late diastole (E/A) ratio patterns (normal, delayed relaxation, pseudonormal, restrictive) can be discerned if viewed within the context of other available clinical information. These patterns evolve from one to another in a single individual, with changes in disease evolution, treatment, and loading condition. They represent a continuum from normal to severe diastolic dysfunction, showing progressively increasing left ventricular (LV) chamber stiffness and subsequently decreasing deceleration time. The combination of Doppler restrictive filling pattern and decreased deceleration time provides important information that helps to differentiate gradations of diastolic dysfunction and has been found to be a potent predictor of prognosis and mortality in various cardiac conditions. When clinical and transthoracic data alone are not sufficient in guiding therapy of congestive heart failure, transesophageal echocardiography can be used to assess most Doppler flows, especially pulmonary venous and left atrial (LA) appendage flows. The use of the multiplane transducer in multiple intermediate scan planes further improves the possibility of optimizing the Doppler incident angle and obtaining the best Doppler recordings of the left upper or right upper pulmonary venous flow. Whereas LV diastolic dysfunction is common in patients with congestive heart failure and appears to be an important predictor of prognosis, little information is available about right ventricular (RV) diastolic dysfunction. The role of RV function in congestive heart failure has probably been underestimated and it is possible that RV diastolic dysfunction assessment is equally important in the follow-up of heart failure patients. Recently, 2 novel echocardiographic technologies for the assessment of ventricular wall dynamics have been developed--color kinesis and tissue Doppler imaging. Both techniques have recently been shown to provide global as well as regional information on LV contraction and filling. Complementary use of both techniques may allow a more complete noninvasive assessment of global and regional systo-diastolic LV function.

Assessment of left ventricular dyssynergy by color kinesis

Color kinesis is a new echocardiographic technique based on acoustic quantification. It has been developed to facilitate the ability to identify contraction abnormalities and has been incorporated into a commercially available ultrasound imaging system. The potential of this technique to improve the qualitative and quantitative assessment of wall motion abnormalities is described. Evaluation of color-encoded images allows detection of decreased amplitude of endocardial motion in abnormally contracting segments as well as a shorter time of endocardial excursion in segments with severely decreased motion. Compared with off-line quantitative studies, color kinesis has the advantage to be used on-line, without time-consuming manual tracing of endocardial boundaries. In addition, a single end-systolic color image contains the entire picture of spatial and temporal contraction and can be digitally stored and retrieved. In patients with proven coronary artery disease, color kinesis had a sensitivity of 88%, a specificity of 77%, and an overall accuracy of 86% in identifying the presence of segmental dysfunction. The practical application of color kinesis might be to improve our ability to distinguish normal from hypokinesis, something that has always been difficult in clinical echocardiography. Segmental analysis of color kinesis images allows objective detection of dobutamine-induced regional wall motion abnormalities in agreement with conventional visual interpretation of the corresponding 2-dimensional views. A method for objective assessment of wall dynamics during dobutamine stress echocardiography would be of particular clinical value, because these images are even more difficult to interpret than conventional echocardiograms. Quantitative assessment of diastolic function may allow objective evaluation of segmental relaxation abnormalities, especially under conditions of pharmacologic stress testing. Acquisition of color kinesis images during dobutamine stress echocardiography, both transthoracic and transesophageal, may facilitate the assessment of hybernating but viable myocardium and enhance the sensitivity in the detection of coronary artery disease.

Noninvasive markers for acute heart transplant rejection in children with the use of automatic border detection

A noninvasive method to detect heart transplant rejection would allow for increased monitoring at reduced risk. Automatic border detection is a new method to assess diastolic abnormalities. The purpose of this study was to determine whether automatic border detection of left ventricular filling detects rejection in children. Nineteen episodes of biopsy-proven rejection in 10 children were retrospectively reviewed. Echocardiograms during rejection were compared with those before rejection and during recovery. Automatic border detection indices were percentage of total left ventricular filling as a result of rapid filling, diastasis, and atrial contraction. The percentage of total ventricular filling during diastasis increased significantly during rejection (10% +/- 6% versus 15% +/- 8%, p = 0.02), and the percentage of filling during the rapid filling phase decreased during rejection (82% +/- 8% versus 77% +/- 11%, p = 0.08). These changes were even more marked for the most severe episodes of rejection. These changes resolved at recovery. Automatic border detection of left ventricular filling patterns are altered during cardiac rejection in children. Filling during diastasis increases significantly, and filling during the rapid filling phase decreases. A prospective analysis is needed to determine whether these changes in filling can obviate the need for cardiac biopsy.

On-line quantitative assessment of left ventricular filling during dobutamine stress echocardiography: a useful addition to conventional wall motion scoring

In order to determine whether the diastolic rate of ventricular volume change obtained on-line with an automatic border detection (ABD) system during dobutamine stress echocardiography (DSE) would provide an interpretation of the diastolic ventricular response to the drug in quantitative terms in the assessment of coronary artery disease, we studied, with ABD and DSE, 59 patients who underwent coronary arteriography within 2 months of the stress test. Eleven patients had normal coronary findings or non-significant coronary lesions. Significant (> or =70% diameter stenosis) coronary artery disease (CAD) was present in 48 patients (81%). Dobutamine stress echocardiography (DSE) to a maximal dose of 50 microg/kg per min was performed in all patients. ABD images were acquired at rest and at the peak of infusion along with conventional two-dimensional images. The following measurements were evaluated: left ventricular end-diastolic volume (LVEDV), left ventricular end-systolic volume (LVESV), left ventricular ejection fraction (LVEF), slope of rapid filling segment (RFS), peak filling rate (PFR), rapid filling phase fractional change (RFFC). Patients with non-significant coronary artery lesions exhibited a hyperdynamic response with an LVEF increment of at least 20% from baseline to peak drug infusion. In these patients the effect of dobutamine produced an increase of RFS from 35.5+/-5.6 to 86.5+/-10.5 ml/s, an increase of PFR from 4.4+/-0.6 to 6.8+/-0.6 EDV/s, and an increase of RFFC from 74+/-8 to 92+/-5% (P<0.001). Of the 48 patients with coronary artery disease, 27 had <20% LVEF increase at peak dobutamine infusion. Four of 22 patients with single vessel disease and 23 of 26 patients with multivessel disease had an abnormal systolic response. After dobutamine infusion single vessel CAD patients showed a decrease of RFS from 33.4+/-5.3 to 26.7+/-5.9 ml/s, a decrease of PFR from 3.8+/-0.7 to 3.0+/-0.7 EDV/s, and a decrease of RFFC from 73+/-6 to 59+/-4% (P<0.001). Multivessel CAD patients showed a decrease of RFS from 32.0+/-5.9 to 23.1+/-4.1 ml/s, a decrease of PFR form 3.8+/-0.6 to 2.8+/-0.6 EDV/s, and a decrease of RFFC from 71+/-5 to 54+/-8% (P<0.001). The overall sensitivity of detecting CAD was 85% for conventional DSE and 90% for ABD-DSE (P=NS). The sensitivities of detecting patients with single vessel and multivessel CAD with conventional DSE were 68 and 92%, respectively, and with ABD-DSE were 91% (P<0.01) and 96% (P=NS), respectively. Our results show that an abnormal diastolic as well as systolic response during on-line quantitative assessment of dobutamine stress echocardiography is a sensitive marker of coronary artery disease and is predictive for the detection of extensive lesions. The described measurements can be utilized to improve the DSE sensitivity in identifying coronary artery disease. On-line quantitation of diastolic indexes with ABD can represent another step toward obtaining uniform results after stress echocardiography.